This application seeks support for the continuation of a research project begun a decade ago to study the life-span development of individual differences in behavior and behavioral dispositions. The application seeks support for continued investigation of several theoretical and empirical issues about the stability of human dispositional characteristics over the life-span, particularly the extent of variation in patterns of stability and change that result from processes of aging and social change. It will apply existing theoretical frameworks and methodological approaches developed on the basis of past empirical studies in the U.S. to relatively new national-level panel data from the U.S. and Great Britain: 1) the Study of American Families (SAF), 2) Americans' Changing Lives (ACL) study, 3) the British Household Panel Study (BHPS), and 4) the National Election Study panels from the 1950s, 1970s and the 1990s. In addition, support is requested for the examination of several theoretically-grounded hypotheses regarding cohort stability and change using existing cross-sectional data from the General Social Survey and National Election Study series. The GSS is a set of 20 surveys conducted from 1972 to 1994 on nationally representative samples of the U.S. The NES series is based on 21 election-year surveys since 1952 on nationally representative samples of the U.S. Evidence is sought for three separate, but not mutually exclusive explanations for human stability and change: cohort or generational explanations of stability/change, life-cycle or aging explanations of stability/change, and historical or period" explanations of individual and social change. These interpretations will be based on decompositions of social change into intra-cohort change and cohort replacement components, supplemented with estimates of molar stabilities using the panel data. Estimates of these components will be obtained using structural equation analysis of latent growth curves employing a variety of different model specifications.